A typical folding stage system of the prior art is proposed in Japanese Application for Registration of Utility Model No. 52-82315 (published under No. 60-25482). The prior folding stage system has a guide post to be fixed to a wall or the like, and a balancer mechanism supporting the rear portion of the stage body for vertical movement. The prior folding stage system also has, on its front portion, wheels to enable the stage body to be moved on a floor. The stage body of the system can be "folded" or stored from a horizontal position on the floor to a vertical position adjacent to the post. Legs are pivotally connected to the bottom of a platform so that the legs make right angles with the platform when supporting the platform on the floor, but change their angles to the platform as the legs are raised away from the floor when the stage body is moved to the vertical position, and become parallel to the platform when the platform is moved to a vertical position.
The inventor hereof proposed a folding stage system similar to the foregoing one in Japanese Application for Registration of Utility Model No. 59-100829 (published under No. 61-16200).
Although with the help of the balancer mechanism, either of the prior folding stage systems must be manually folded or unfolded and, hence, are not suitable for use as a stage unit of a full-size folding stage system with a proscenium wall. It is necessary to use electrically-operated stage units to produce such a full-size stage system which can be folded and unfolded without labor. Thus, the inventor hereof proposed an electrically-operated (, or electrically folded and unfolded ) stage unit for such a full-size stage system in Japanese Patent Applications No. 59-120395 (published Jan. 7, 1986 under No. 61-1769). The inventor also proposed such an electrically-operated stage unit in Japanese Patent Application No. 60-298461 (published July 16, 1987 under No. 62-160371).
However, the stage proper of a stage unit used for a folding stage system of FIG. 5 of Japanese Patent Application No. 59-120395 is folded (, or moved to a vertical position) and unfolded (, or moved to a horizontal position on a floor) not only by a first operating mechanism, but also with the help of a second operating mechanism which is chiefly used to move the proscenium wall. It is also the case with the stage unit of Japanese Patent Application No. 60-298461.